Construction of cams for machinery



(No Model.

J- BRADY.

Construction of Cams for Machinery. No. 231,145. Patented Aug. 17,1880.

Fllll. F IC-E,

UNITED STATES PATENT ()FFICE.

JAMES BRADY, OF. BROOKLYN, NEIV YORK.

CONSTRUCTION OF CAMS FOR MACHINERY.

SPECIFICATION forming part of Letters Patent No. 231,145, dated August 17, 1880.

Application filed J une 29, 1880.

To all whom it may concern:

Be it known that I, J AMES BRADY, of Brooklyn, Kings county, New York, have invented certain new and useful Improvements in the Construction of Cams for Machinery, of which the following is a specification.

This invention relates more especially to grooved cylindrical cams in which a roller attached to the part to which the action of the cam is transmitted runs in the groove of the cam. In this form of cam as heretofore made a certain amount of play always exists between the roller and the groove, as the roller must be made somewhat smaller than the groove to avoid bearin g on both sides thereof, and if this play is prevented by making the roller a full fit for the groove, it then bears at both sides and produces great friction, which neutralizes all advantages to be gained by the use of a roller.

Now, my invention aims to so construct such cams as to prevent all playbetween the roller and groove, as well as to prevent undue friction between the same, and thus enable such cams to produce accurate and positive motions in an easy and efficient manner.

To this end the main feature of my invention may be stated to consistin providing the part actuated by the cam with two independent rollers, placed one above the other, and each bearing independently on opposite sides of the groove, and also in making the groove of a stepped or rabbeted form in cross-section, with an independent roller-bearin g upon opposite sides and steps of the groove, as hereinafter fully set forth.

Figure 1 of the drawings annexed presents a plan view of an ordinary cylindrical grooved cam and a part vibrated or actuated thereby constructed according to my invention. Fig. 2 is a vertical section thereof and Fig. 3 is a similar view to the latter, representing a modification.

As illustrated in the drawings, the body a a of the cam may be constructed in any suitable or approved manner, and the groove thereof may have any form of continuation according to the motion required to be produced, as will be readily understood, and the lever b or other part actuated by the cam is of course engaged at its free end with the groove of the cam.

(No model.)

Now, according to my invention, I form the groove of the cam of stepped or rabbeted form in cross-section, as shown in Fig. 2 and by full and dotted lines in Fig. 1, the steps being arranged coincident at opposite sides of the groove, as shown, and in lieu of fitting the engaging end of the actuating part b with one roller to engage the groove, two distinct rollers are employed, each free to rotate independently on the stud which connects them to the part I). These rollers are placed one above the other, sufficiently separated so as to revolve independently without contact with each other, and they are both of a diameter exactly equal to the distance between the two most salient portions or steps of the groove, and one roller bears against one of these steps and the other against the opposite step at diametrically-op posite positions, as seen best in Fig. 2. It will thus be seen that by this construction there can exist no appreciable play between the camgroove and the actuated part, for the latter is in constant engagement with both sides of the cam-groove by independent roller-bearings, which obviate all undue friction, and furthermore cause the opposite inclines of the cam to come into instant action alternately on the rollers in true time, thus rendering the motion of the actuated part smooth and easy, as well as accurate and positive, relatively to the changes of the cam, and also requiring less power and enabling the cam to be driven with greater rapidity.

If desired, the rollers maybe made slightly tapering, and the bearing-edges of the camgroove correspondingly inclined, so-that wear may be counteracted by adjusting the rollers up or down in the groove in a well-known manner. I

In some cases the cam-groove may be of ordinary form, as seen in Fig. 3, while the independent rollers on the -actuated part may be arranged slightly eccentric to each other, or in stepped position, one bearing on one side of the groove and the other on the opposite side, with substantially the same efiect as in the first case. This modification, however, is not specially recommended, but may be adopted in special cases;

From the above description those acquainted with mechanics will, without further state ment, readily appreciate the advantages of cams thus constructed, especially for. sewing, engraving, or other machinery where rapid, accurate, and easy motions are required.

What I claim as my invention is 1. The combination, with a grooved caln, of a part actuated thereby provided with two or more independent en gaging-rollers placed one above the other, both fixed on said actuated part and engaged with said groove at the same point, and each bearing independently on opposite sides of the groove, substantially as herein shown and described.

2. A grooved cam constructed with a groove of stepped form in cross-section, in combination with a part actuated thereby provided with two independent rollers engaged with said groove, and each bearing upon opposite steps of the groove, substantially as and for the purpose set forth.

JAMES BRADY.

Witnesses EDWARD H. WALES, CHAS. M. HIGGINS. 

